Frames for use in two dimensional paper chromatography



April 23, 1963 J. GREEN ETAL 3,086,439

FRAMES FOR USE IN TWO DIMENSIONAL PAPER CHROMATOGRAPHY Filed March 11, 1960 2 Sheets-Sheet l 7 Fl G. 3

j INVENTORS ATTO RN EY April 23, 1963 J. GREEN ETAL FRAMES FOR USE IN TWO DIMENSIONAL PAPER CHROMATOGRAPHY Filed March 11, 1960 2 Sheets-Sheet 2 ATTORNEY United States Patent 3,086,439 FRAMES FOR USE IN TWO DIMENSIQNAL PAPER CHRGMATDGRAPHY Joseph Green, London, and Peter Ridgway Watt, Reigate,

Surrey, England, assignors to Vitamins Limited, London, England, a British company Filed Mar. 11, 1960, Ser. No. 14,225 Claims priority, application Great Britain Mar. 19, 1959 3 Claims. (Cl. 95-100) This invention relates to a frame for use in two dimensional paper chromatography. Such chromatography is an essential step in many assay procedures.

Rigid frames which hold a number of paper sheets so that many chromatograms can be run at once are known and it is an object of the invention to provide an improved such frame. Accordingly, the invention provides a frame which includes two end plates secured together in parallel face to face relationship, paper supporting bars extending perpendicularly between the end plates and provided with aligned transverse slots positioned so as to receive edge portions of paper sheets inserted in the frame parallel to the end plates thereby to space the sheets from one another, and skewers which can be moved lengthwise into or out of longitudinal bores in the supporting bars. The insertion of the skewers serves to pierce holes in the portions of the paper sheets in the slots so as to secure the sheets in position.

Some chromatography systems use solvents, for example aqueous alcohol, which have the effect of causing a gradual expansion of the paper sheets across the fibre axis of the sheets so that the papers tend to buckle sometimes to such an extent that they even touch each other. With known frames it is necessary to space the sheets at least two centimetres apart if they are not to touch during development and this inefficiently utilises both the developing tank and the solvent. Furthermore, the paper sheets still touch each other on frequent occasions and are therefore spoiled even with a two centimetre spacing. An embodiment of this invention provides, as a means of avoiding this disadvantage, a frame which can accept and locate papers without the use of punched holes and which will keep the paper sheets fiat under all conditions thereby to permit them to be arranged closer together than is usual. In this embodiment, the supporting bars are mounted so that they can move outwards of the frame and are spring loaded in the outward direction, means are provided for releasably locking the bars in a desired position when it is desired to load the sheets in the frame. When the frame has been loaded, the locking device can be released so that the sheets can be maintained in a flat condition under the influence of the spring loading of the supporting bars.

A preferred embodiment of the invention is illustrated in the accompanying drawings of which:

FIGURE 1 is an end view and FIGURE 2 is a side view of a chromatography frame while FIGURES 3 and 4 are sectional views of details.

The chromatography frame illustrate-d comprises end plates 1 and 2 which are preferably of sheet aluminium or stainless steel and are arranged parallel with, and spaced from, each other in face to face relationship by means of fixed spacers 3 secure-d at side edges of the plates. The length of the spacers 3 depends on the number of chromatograms which the frame is intended to contain.

Two pairs of paper supporting bars 4 and 5 respectively extend perpendicularly to the end plates between opposite top and bottom corners of the plates. In order that these bars can be capable of movement outwards of the frame, they have a floating connection with the end 3,li8,439 Patented Apr. 23, 1963 plates. The ends of the supporting bars 4 and 5 are pivotally connected with carrier arms 6 running in diagonal directions along the insides of the end plates 1 and 2. These arms 6 have bushes 7 extending through apertures 8 in the end plates and fitted with bosses 9 outside the end plates and on which bear light stainless steel steel springs 10 to load the bars 4 and 5 for outward movement. Each supporting bar has a series of spaced transverse slots adapted to locate the paper sheets (only one, 11, of which is shown) in spaced relationship parallel to the end plates. The slots 12 on the bars 5 which are at the bottom of the frame when it is in use are preferably arranged to receive the bottom edges of the paper sheets 11 near the corners of the sheets and the slots 13 in the other two bars 4 are preferably arranged to receive the side edges of the sheets near the top corners. Each supporting bar has a longitudinal bore in which a removable skewer 14, i.e. a pointed rod, is located.

Locking means are provided to fix the supporting bars in a loading position at the four corners of a square or rectangle. Such locking means includes two clover leaf cams 15 arranged on the outside of each end plate and linked by a handle 16 outside the frame. The carrier arms 6 have cam follower members 17 extending through radial slots 17a in the end plates and engaged with these cams 15.

When the frame is to be loaded, the skews 14 are removed from the supporting bars 4-, 5 and the paper sheets 11 are inserted into the frame and engaged in the locating slots 12, 13. The skewers 14 are then reinserted in the longitudinal bores in the bars 4-, 5 during which operation they will pierce holes in the sheets. When all the skewers have been completely re-inserted in the bores the locking device is released so that there is a tendency for the paper sheets, the corners of which are held by the skewers, to be stretched under the action of the loading springs 10 as the cam followers 17' of the carrier arms 6 are free to move outwards. The loading by the springs 10 is such that if one of the sheets 11 is tighter than the other, the holes produced in that sheet by the skewers 14 may tear very slightly. In this way the frme can move to stretch the other sheets evenly and no further tearing will take place as soon as the strain is taken by two or more sheets. Thus, slightly uneven loading is compensated. The sheets must be loaded with their fibre axes parallel.

The design of the stretching system is quite important. When the frame is first put into a tank containing aqueous solvent the bottom edges of the sheets are wetted before the remainder of each sheet is eflected either by rising solvent or by vapour. Subsequently, expansion takes place in the middle and upper parts of the sheets until the paper is in complete equilibrium. Hence, the general shape of a square sheet of paper changes through a series of trapezia and eventually becomes an approximate rectangle. The ratio of the length to the width of the final rectangle depends on the solvent mixture employed. For example, with a square sheet having a 20 centimetre side, pure water gives an extension of perhaps 3 mm. at right angles to the fibre axis on Whatman No. 1 paper while producing little measurable extension along the fibre axis. On the other hand, to aqueous ethanol produces a definite extension of some 0.5 mm. along the fibre axis on a 20 x 20 cm. paper, While the extension across the axis is reduced to about 2 mm. From this it will be clear that the corners cannot expand radially from the centre but describe curved paths, varying with each solvent used. In order to allow this movement to take place freely the frame of the present invention can be arranged to permit two adjacent corners to move away from each other on straight slides while the other two are floated on springs and may take up any position in a small area, all corners moving independently of each oses-as r; all

other. The paper edge running on the slides expands linearly whilst remaining at a fixed distance from the edge of the frame; and this is normally the edge dipping in the aqueous solvent in the tocopherol assay method.

All the moving parts of the frame are preferably fitted with polytetrafluoroethylene bushes to minimise friction.

What we claim is:

l. A chromatography frame comprising two end plates secured together in parallel face to face relationship, paper supporting bars ext nding perpendicularly between the end plates and provided with aligned transverse slots positioned so as to receive edge portions of paper sheets inserted in said frame parallel to said end plates thereby to space said sheets from one another, and said bars being provided with longitudinal bores, springs urging said bars for movement in apertures outwards of said frame, skewers which can be moved lengthwise into and out of said longitudinal bores, and means for releasably locking said supporting bars in a desired position.

2. A chromatography frame comprising two end plates; means for securing said end plates in spaced face to face relationship; paper supporting bars extending between said end plates and connected therewith in a manner which permits them to move outwards of the frame, each of said bars having a longitudinal passage and transverse slots positioned so as to receive edge portions of paper sheets inserted in said frame parallel to said end plates thereby to space said sheets from one an- 4 other; springs which are mounted on said end plates and urge said supporting bars outwards of said frame; skewers which can be moved lengthwise into and out of said longitudinal passages; and releasable means for locking said supporting bars in a desired position.

3. A chromatography frame comprising two end plates having apertures therein; means for securing said end plates in spaced face to face relationship; carrier arms arranged inside said end plates; bushes on said carrier arms which are movable in said apertures in said end plates; bosses fitted on said bushes; springs bearing on said bosses to urge them to move in said apertures outwards of the frame; paper supporting bars extending between said end plates and mounted on said carrier arms, said supporting bars having aligned transverse slots positioned to receive edge portions of paper sheets inserted in the frame parallel to said end plates and having longitudinal passages; cam followers on said carrier arms; rotatable cams mounted on said end plates and bearing on said cam followers to cause movement of said carrier arms; a handle for rotating said cams; and skewers which can be moved lengthwise into and out of said longitudinal passages to secure or release said paper sheets.

Dye Mar. 12, 1918 Bechstein et al Dec. 12, 1922 

3. A CHROMATOGRAPHY FRAME COMPRISING TWO END PLATES HAVING APERTURES THEREIN; MEANS FOR SECURING SAID END PLATES IN SPACED FACE TO FACE RELATIONSHIP; CARRIER ARMS ARRANGED INSIDE SAID END PLATES; BUSHES ON SAID CARRIER ARMS WHICH ARE MOVABLE IN SAID APERTURES IN SAID END PLATES; BOSSES FITTED ON SAID BUSHES; SPRINGS BEARING ON SAID BOSSE TO URGE THEM TO MOVE IN SAID APERTURES OUTWARDS OF THE FRAME; PAPER SUPPORTING BARS EXTENDING BETWEEN SAID END PLATES AND MOUNTED ON SAID CARRIER ARMS, SAID SUPPORTING BARS HAVING ALIGNED TRANSVERSE SLOTS POSI- 